From 3ec21a949b0887e32bbffcdb38a5738abfe8cfd0 Mon Sep 17 00:00:00 2001
From: Wojciech Kosior <kwojtus@protonmail.com>
Date: Sat, 5 Sep 2020 16:58:33 +0200
Subject: add add instruction together with bench

---
 Makefile                                    |  3 ++-
 design/stack_machine.v                      | 28 +++++++++++++++++++++-------
 tclasm.tcl                                  |  5 +++++
 tests/stack_machine_add/instructions.s.tcl  | 23 +++++++++++++++++++++++
 tests/stack_machine_add/test.v              |  1 +
 tests/stack_machine_add/words_to_verify.mem |  6 ++++++
 6 files changed, 58 insertions(+), 8 deletions(-)
 create mode 100755 tests/stack_machine_add/instructions.s.tcl
 create mode 120000 tests/stack_machine_add/test.v
 create mode 100644 tests/stack_machine_add/words_to_verify.mem

diff --git a/Makefile b/Makefile
index 8f4e729..6f2227f 100644
--- a/Makefile
+++ b/Makefile
@@ -36,7 +36,8 @@ STACK_MACHINE_TESTS := \
 	store \
 	load_store \
 	multiinstructions_load_store \
-	tee
+	tee \
+	add
 
 # Add other tests here if You need
 TESTS := \
diff --git a/design/stack_machine.v b/design/stack_machine.v
index 04b1285..d79a136 100644
--- a/design/stack_machine.v
+++ b/design/stack_machine.v
@@ -118,6 +118,9 @@ module stack_machine_new
    wire 	      stack_shrinks;
    assign stack_shrinks = instruction[13] == 1'b1 && !set_im;
 
+   wire 	      stack_shrinks_by_1;
+   assign stack_shrinks_by_1 = stack_shrinks && instruction[12] == 1'b1;
+
    wire 	      stack_shrinks_by_2;
    assign stack_shrinks_by_2 = stack_shrinks && instruction[12] == 1'b0;
 
@@ -193,7 +196,9 @@ module stack_machine_new
 			instruction[11:7] == 5'd0;
 
    /* Instructions, that shrink stack */
-   /* none now */
+   wire 	      instr_add;
+   assign instr_add = !set_im && !use_im && stack_shrinks_by_1 &&
+		      instruction[11:0] == 12'd0;
 
    reg 		      halt; /* Set once a halt instruction is encountered */
    assign finished = halt;
@@ -279,9 +284,6 @@ module stack_machine_new
 	   STEP_EXECUTING : begin
 	      first_execution_tick <= 0;
 
-	      if (instr_halt)
-		halt <= 1;
-
 	      if (((stack_grows || stack_shrinks || load || store) &&
 		   first_execution_tick) ||
 		  (load_store_uncompleted &&
@@ -425,14 +427,26 @@ module stack_machine_new
 	      else
 		im <= 32'bx;
 
-	      if (instr_const && first_execution_tick)
-		r1 <= im_effective;
+	      /* Instructions, that do not change stack size */
+	      if (instr_halt)
+		halt <= 1;
 
-	      if (instr_tee)
+	      if (instr_nop)
 		r1 <= r1;
 
 	      if (instr_set_sp)
 		`SET_SP(im_effective);
+
+	      /* Instructions, that grow stack */
+	      if (instr_tee)
+		r1 <= r1;
+
+	      if (instr_const && first_execution_tick)
+		r1 <= im_effective;
+
+	      /* Instructions, that shrink stack */
+	      if (instr_add && first_execution_tick)
+		r1 <= r1 + r0;
 	   end // case: STEP_EXECUTING
 	 endcase // case (step)
       end // else: !if(RST_I)
diff --git a/tclasm.tcl b/tclasm.tcl
index c00fe18..f5646a2 100644
--- a/tclasm.tcl
+++ b/tclasm.tcl
@@ -96,6 +96,11 @@ proc tee {} {
 }
 
 
+proc add {} {
+    puts 0011000000000000
+}
+
+
 proc _store {address_part} {
     puts 011111100[__to_binary $address_part 7]
 }
diff --git a/tests/stack_machine_add/instructions.s.tcl b/tests/stack_machine_add/instructions.s.tcl
new file mode 100755
index 0000000..c0a9449
--- /dev/null
+++ b/tests/stack_machine_add/instructions.s.tcl
@@ -0,0 +1,23 @@
+#!/usr/bin/env tclsh
+
+source tclasm.tcl
+
+### store 2 values to memory, load them back, add them and store the result
+
+set_sp 0
+
+const 12345678
+store h1EEE0
+const 40302010
+store h1EEE4
+
+const 8
+
+load h1EEE0
+load h1EEE4
+# adding 40302010 to 12345678 should yield 52647688
+add
+# will write to h1EEE0 + 8 = h1EEE8
+store+ h1EEE0
+
+halt
diff --git a/tests/stack_machine_add/test.v b/tests/stack_machine_add/test.v
new file mode 120000
index 0000000..f5b6a59
--- /dev/null
+++ b/tests/stack_machine_add/test.v
@@ -0,0 +1 @@
+../stack_machine_store/test.v
\ No newline at end of file
diff --git a/tests/stack_machine_add/words_to_verify.mem b/tests/stack_machine_add/words_to_verify.mem
new file mode 100644
index 0000000..601e8fd
--- /dev/null
+++ b/tests/stack_machine_add/words_to_verify.mem
@@ -0,0 +1,6 @@
+// address  value
+   1EEE0    BC614E  // 12345678 in hex is BC614E
+
+   1EEE4    266F5BA // 40302010 in hex is 266F5BA
+
+   1EEE8    3235708 // 52647688 in hex is 3235708
-- 
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